Description

The Trace-Command cmdlet configures and starts a trace of the specified expression or command. It works like Set-TraceSource, except that it applies only to the specified command.

Parameters

-ArgumentList <Object[]>

Specifies the parameters and parameter values for the command being traced. The alias for ArgumentList is Args. This feature is especially useful for debugging dynamic parameters.

Required?

false

Position?

named

Default Value

Accept Pipeline Input?

false

Accept Wildcard Characters?

false

-Command <string>

Specifies a command that is being processed during the trace.

Required?

true

Position?

2

Default Value

Accept Pipeline Input?

false

Accept Wildcard Characters?

false

-Debugger

Sends the trace output to the debugger. You can view the output in any user-mode or kernel mode debugger or in Visual Studio. This parameter also selects the default trace listener.

Required?

false

Position?

named

Default Value

Accept Pipeline Input?

false

Accept Wildcard Characters?

false

-Expression <scriptblock>

Specifies the expression that is being processed during the trace. Enclose the expression in braces ({}).

Required?

true

Position?

2

Default Value

Accept Pipeline Input?

false

Accept Wildcard Characters?

false

-FilePath <string>

Sends the trace output to the specified file. This parameter also selects the file trace listener.

Required?

false

Position?

named

Default Value

Accept Pipeline Input?

false

Accept Wildcard Characters?

false

-Force

Allows the cmdlet to append trace information to a read-only file. Used with the FilePath parameter. Even using the Force parameter, the cmdlet cannot override security restrictions.

Required?

false

Position?

named

Default Value

Accept Pipeline Input?

false

Accept Wildcard Characters?

false

-InputObject <psobject>

Provides input to the expression that is being processed during the trace.

You can enter a variable that represents the input that the expression accepts, or pass an object through the pipeline.

Required?

false

Position?

named

Default Value

Accept Pipeline Input?

true (ByValue)

Accept Wildcard Characters?

false

-ListenerOption <TraceOptions>

Adds optional data to the prefix of each trace message in the output. The valid values are None, LogicalOperationStack, DateTime, Timestamp, ProcessId, ThreadId, and Callstack. "None" is the default.

To specify multiple options, separate them with commas, but with no spaces, and enclose them in quotation marks, such as "ProcessID,ThreadID".

Required?

false

Position?

named

Default Value

Accept Pipeline Input?

false

Accept Wildcard Characters?

false

-Name <string[]>

Determines which Windows PowerShell components are traced. Enter the name of the trace source of each component. Wildcards are permitted. To find the trace sources on your computer, type "Get-TraceSource".

To specify multiple options, separate them with commas, but with no spaces, and enclose them in quotation marks, such as "Constructor,Dispose".

Required?

false

Position?

3

Default Value

Accept Pipeline Input?

false

Accept Wildcard Characters?

false

-PSHost

Sends the trace output to the Windows PowerShell host. This parameter also selects the PSHost trace listener.

Required?

false

Position?

named

Default Value

Accept Pipeline Input?

false

Accept Wildcard Characters?

false

<CommonParameters>

This command supports the common parameters: Verbose, Debug, ErrorAction, ErrorVariable, OutBuffer, OutVariable, WarningAction, and WarningVariable. For more information, see about_CommonParameters.

Inputs and Outputs

The input type is the type of the objects that you can pipe to the cmdlet. The return type is the type of the objects that the cmdlet returns.

Inputs

System.Management.Automation.PSObject

You can pipe objects that represent input to the expression to Trace-Command.

Outputs

System.Management.Automation.PSObject

Returns the command trace in the debug stream.

Notes

Tracing is a method that developers use to debug and refine programs. When tracing, the program generates detailed messages about each step in its internal processing.

The Windows PowerShell tracing cmdlets are designed to help Windows PowerShell developers, but they are available to all users. They let you monitor nearly every aspect of the functionality of the shell.

A "trace source" is the part of each Windows PowerShell component that manages tracing and generates trace messages for the component. To trace a component, you identify its trace source.

A "trace listener" receives the output of the trace and displays it to the user. You can elect to send the trace data to a user-mode or kernel-mode debugger, to the host or console, to a file, or to a custom listener derived from the System.Diagnostics.TraceListener class.

When you use the Command parameter set, Windows PowerShell processes the command just as it would be processed in a pipeline. For example, command discovery is not repeated for each incoming object.

The names of the Name, Expression, Option, and Command parameters are optional. If you omit the parameter names, the unnamed parameter values must appear in this order: Name, Expression, Option or Name, Command,-Option . If you include the parameter names, the parameters can appear in any order.

Example 1

C:\PS>trace-command -name metadata,parameterbinding,cmdlet -expression {get-process notepad} -pshost
Description
-----------
This command starts a trace of metadata processing, parameter binding, and cmdlet creation and destruction of the "get-process notepad" expression. It uses the Name parameter to specify the trace sources, the Expression parameter to specify the command, and the PSHost parameter to send the output to the console. Because it does not specify any tracing options or listener options, the command uses the defaults, "All" for the tracing options, and "None" for the listener options.

Example 2

C:\PS>trace-command -name commandprocessor,pipelineprocessor -command get-alias -argumentlist "ghy" -option executionflow -listenerOption "timestamp,callstack" -filepath c:\test\debug.txt
Description
-----------
This command starts a trace of the command processor and pipeline processor while processing the "get-alias cd" command.
It uses the Name parameter to specify the trace sources, the Command parameter to specify the command, the ArgumentList parameter to specify the parameters of the Get-Alias command, the Option parameter to specify tracing options, and the ListenerOption parameter to specify the fields in the trace message prefix. The FilePath parameter sends the output to the C:\Test\Debug.txt file.

Example 3

C:\PS>$a = "i*"
C:\PS> trace-command parameterbinding {get-alias $input} -pshost -inputobject $a
Description
-----------
These commands trace the actions of the ParameterBinding operations of Windows PowerShell while it processes a Get-Alias expression that takes input from the pipeline.
In Trace-Command, the InputObject parameter passes an object to the expression that is being processed during the trace.
The first command stores the string "i*" in the $a variable. The second command uses the Trace-Command cmdlet with the ParameterBinding trace source. The PSHost parameter sends the output to the console.
The expression being processed is "get-alias $input", where the $input variable is associated with the InputObject parameter. The InputObject parameter passes the variable $a to the expression. In effect, the command being processed during the trace is "get-alias -inputobject $a" or "$a | get-alias".